Forging is a manufacturing process where metal is pressed, pounded or squeezed (these terms are used interchangeably herein) under great pressure into high strength parts known as forgings. The process is normally (but not always) performed hot by preheating the metal to a desired temperature before it is worked.
The forging process can create parts that are stronger than those manufactured by any other metalworking process. This is why forgings are almost always used where reliability and human safety are critical. Forgings are often used as component parts contained inside assembled items such as ships, oil drilling equipment, engines, and many other kinds of equipment.
For example, current energy production incorporating nuclear, wind or thermal power plants employ large-scale turbine/electric motor generator systems. Within the turbine/generator system is a large, high speed rotating shaft, designated as the rotor. The complete rotor train within these power plants includes the high, intermediate, and low pressure turbine rotors, in combination with the generator rotor. Products that are in these areas that may be forged include, but are not limited to 1) solid 2-pole and 4-pole rotors for generators and motors, 2) gas generator rotors, 3) steam generator rotors, 4) wind generator rotors, 5) hydro turbine rotors, 6) aero derivative turbine shafts utilizing solid step forgings (due to limitations of conventional open die forging of ingot steel).
Forgings are typically completed by subjecting the forging to a machining or finishing process. The process of machining removes excess material from a forging using a machine tool.
Thus, a conventional manufacturing method for these forged rotors involves the acquisition of a cylindrical alloyed-steel forging, representative in excess of the maximum diameter and length of the finished rotor product. Sections of the forged cylinder are removed through precision machining to create a rotor geometry consisting of reduced cylindrical sections at both ends of the rotor, with a central section, precision machined to contain segmented geometries (disks) which extend to the maximum outer diameter of the rotor.